We’re building a litter box/hay feeder/perch for Cashew, and I was wondering if anyone had any input on this:

The wooden box will hold his existing litter box, and provide a frame which holds a hay feeder on one side, and a shelf on the other.  While Cashew doesn’t generally pee outside his litter box, my husband was concerned at leaving the wood totally untreated.

I read that for food safe surfaces, such as “butcher block” counter tops, treatment/upkeep with either mineral oil or walnut oil is considered safe, at least for humans.  I also recall reading an article on rabbit.org where a type of eye drops made of mineral oil and petrolatum were recommended for a bunny with chronic watery eyes, so I’m assuming that mineral oil is at least safe for bunnies in those quantities.

Certainly I think it would be safer than any kind of polyurethane finish.  He’s not a big chewer, but anything I wouldn’t be able to eg apply to his fur or he couldn’t lick up a drop of, I’m not even going to consider.  He’s full of surprises, and I don’t want to one day find out that he just loves the taste of polyurethane. O_O

Does anyone else have any kind of experience or knowledge with treating wood in a way that’s bunny safe?  Is mineral oil acceptable?  I believe I would rub it into the wood, leave it for a while, and then wipe off any excess.  I know walnuts aren’t something we want to feed our bunnies, but is the oil acceptable/preferable to mineral oil?

Thanks so much for any help!